To succeed with this premise, you need to walk a thin line between treating the story seriously and understanding the inherent goofiness of it. From what I've heard, Krampus did not pull this off.

I think the reason that Rare Exports is able to pull this off is that it takes it's time getting to the full reveal. It uses the time well by establishing the stakes and endearing you to the characters. It is serious during this period, and makes the fear reasonable by framing it with a child's point of view. By the time the movie gets goofier, you're already fully on board with it.